1. Field of the Invention
The present invention relates to an image forming apparatus that receives printing data from a device which is connected to the image forming apparatus through a network.
2. Description of the Related Art
An image forming apparatus includes an internal storage device for storing printing data which is received from a personal computer (PC). The internal storage device is a hard disk, for example. However, the printing data may leak from the internal storage device. Further, it is known that a fraudulent operation may be performed on the image forming apparatus through the internal storage device.
The printing data which is transmitted from the PC to the image forming apparatus is described in a Page Description Language (PDL). A language specification of the PDL includes a function to operate a file system of the internal storage device of the image forming apparatus. Accordingly, it is possible for an outsider to create printing data for removing, editing, and/or reading a file in accordance of the script language of the PDL (e.g., PJL, PCL, RPDL, PDF, or PostScript), which is supported by the image forming apparatus, and access the internal storage device.
As a countermeasure, it may be considered to restrict access to the internal storage device (cf. Patent Document 1 (Japanese Unexamined Patent Publication No. 2011-216089), for example). Patent Document 1 discloses a technique for allowing or denying access to a printer language execution system depending on a user. In an image forming apparatus according to Patent Document 1, when a user requests to execute a printer language command for the image forming apparatus, the image forming apparatus determines whether the user is granted a right to execute the printer language command, based on a printer language policy setting for the user. When the image forming apparatus determines that the user is granted the right to execute the printer language command, the image forming apparatus executes the command.
Unfortunately, for protection of the internal storage device, it is not sufficient only to restrict execution of a PDL command on a user-by-user basis. In many cases, an image forming apparatus supports a plurality of page description languages. Depending on a page description language, ease of handling the page description language or an extent of disclosure of the grammar varies. For example, since the PostScript is text-based, it is easy to create printing data by the PostScript. In contrast, since the RPDL (registered trade mark) is binary-based, and its grammar is not disclosed to a general user, it is difficult to create printing data by the RPDL.
Even if a user, who is allowed to execute a PDL command, does not have any malicious intent, if the user creates printing data by the PostScript and accesses a file in the internal storage device, it is possible that the file in the internal storage device is leaked or altered.
There is a need for enhancing security of an image forming apparatus when the image forming apparatus performs a predetermined control according to received printing data.